Underreamer



Patented Dec., )18, i923.

untranstares iniciar-mr. nr. swnn'rntan, or Kansas Grrr, MISSOURI.

UNDERBEAMER Application led Octoberl 1B, 1920. Serial No. 417,573.-

Toall lwhom, it may concern:

Be it known that l, MICHAEL M. SWEET- MAN, a citizen of the UnitedStates, residing at Kansas City, in the county of Jackson o and State ofMissouri, have invented certain new and useful Improvements inUnderreamers, of which the following is, a

specilication. ,y y

rThis invention pertains to underreamers l@ tor well drilling, and thestructure is designed or use more particularly with deep wells'wlierethe soil is 'such that diliiculty inheresfin' cementing the casing inits linal position. Various structures have heretol@ fore beendevisedand patented for underreaming, but difficulty obtains in theoperation of such tools where a rotary. drill rod has to be employed,for instance, in deep wells of Texas. 2@ be made to properly perform itsfunction and produce a chamber at the lower portion of the well intowhich the cement may flow, the wells may blow out.

rl`he structure which forms the basis of `the present invention isillustrated in the accompanying drawings wherein,-

Fig. 1 is a vertical vlongitudinal section of the underreamer -withthecutters shown in their extended operative position; an

Fig.y 2 a horizontal sectional view taken on the line llt-ll of Fig. 1.

ln the-drawing, 1 denotes the. mandrel or stock of the tool having abox' 2 formed at its upper .end and a pin 3 at its lower end. Openingfrom the lower portion `of the threaded box 2 is a cylinder a in whichis mounted a piston 5. Said piston has attached to it a piston rod 6,the lowerend of which is fashioned intoa double-face rack 7 or the rackmay be formed as a separate elementV and attached to the rod. The pistonrod 6 passes chamber or bore 4 which is a virtual continuation o thecylinder It. A spring 8 resting at its lower end upon an inwardlyprojecting shoulder 9 and chamber It, contacts the under face of thepiston and tends to elevatel said piston and consequently to `raise thepiston rod and the rack element. By-pass ports l() are formed in theside wall of the lower portion of the cylinder t so that when the pistonis in theposition shown in Fig. l the water which is forced downwardlythrough the drill rod or tube will pass through said ports Unless theunderreamer canV .which they I derreaming operation downwardly through ay housed within the.

below the iston and into the chamber 4, thence finding its way outwardlyaround the various elements, such Vas the cutters or bits 11 and 12.Said bits may be of any approved type. Each bit (the bits beingduplicates) is mounted upon a pin 13 which extends through the body ofthe stock or mandrel 1. Said mandrel is provided with oppositelydisposed slots 14. extending through the" body thereof and in whichslots the bits are 'mounted Each bit is provided with a circular rack,as 15, which cooperates with the adjacent rack element of the member 7,so yl that as the rack is moved downwardly into the position shown inFig. 1 the bits will be swung outwardly and as the rack is movedupwardly the bits will be rocked and swung downwardly passing into theslots 14 by are housed.

lin operation a fish-tail cutter may be mounted uponthe pin 3 in orderto drill an extension of the hole, or if the hole is of sufficientdepth, a suitable guide member of any form may be secured upon the'pin.rThis arrangement acts to center and guide the tool. `When itis desiredto eliect the unthe tool isplaced upon the lower end of the drill stemand lowered d to position. lWhen it reaches' a point where the bits or4cutter blades 11 and 12 may be lprojected outwardly to begin -thecutting operation, water under presseure is forced downwardlyl throughthe stem and into the cylinder 4. 'l he pressure will force the piston 5downwardly, placing the spring under compression and forcing the bitsultimately outwardly .and into. the position shown'in Figl. Then throughthe manipulation of the drill stem the blades will be carried around andthe undercut or reamed out chamber, as 16, produced. This Chamberdesired vdepth and of any desired diameter, the latter being dependentsolely upon the length of the bits. The'pressure of the water is suchthat the piston will be held in its downward position so that the waterwilltravel downwardly through the by-pass chamber 4a, around the pistonrod 6, and outwardly through the slots 14, commingling with the soilwhich is loosened by the bits. Such mixture of water and soil, or, ineffect, the'1nud,will be carried upwardly through the well casing,denoted by 17, and discharged as usual. Then the undermay'be made of anySeo not

ports 10, through the .reamed opening or chamber has been made ofsuilcient size the Water supply will be cut 0H, whereupon the/spring 8will exert an upward pressure to raise the piston and its attachedpartsand the rack will tend to swing the bits inwardly into. the slots oropenings 14. As the mandrel is drawn up- Wardly, and in the eventtliejbits should i sticky they Will contact the lower end of the casing17 and be forced downwardly into their closed position thereb thecurvature b ot' the back ,6 of the.,bits assisting in this action. l

YWhat is claimed is :1.,-

Lian underreamer, the combination of a mandrel provided with a cylinderin its upper portion and with Y( disposed slots formed inthe side walltherea pair vof oppositely drel' to permit passage of water below thepiston and outwardlyithrough the/body of the mandrel when the piston isforced downwardly by the Water pressure; abit pivotally mounted in eachof the slots aforesaid; a

gear formed upon each of said bits a, double face rack cooperating withthe gears of the its; a piston rodN extending from the rack andconnected to the piston; and a spring located beneath the piston andservingto elevate the same when the Water pressure is i Withdrawntherefrom. y

lin testimony whereof li have signed my name to this specification. Y

- `MIUCITIAEL M. SWEETMAN.

